Well, I got my Z5's in today. Spent only around 3 hours till now, but I'm already sold on them. Superb. You can just tell when something is just going to have synergy with the rest of your equipment. What took me by surprise was that the larger, harder silicone tips they came in the box are the way to go for me. The L comply sized foams that worked so well on the triple-fi's could hardly fit in my ears ( T-200's ), so I tried Medium comply's as well, but they took some of that brilliant 3d soundstage I'm getting from the Z5's away. I've been using the Z5's with the fiio e12a amp from the start and I don't see me having any need to use them un-amped, so hopefully that will help with the burn in.
Just one last thing I was going to ask. If you were going to upgrade your DAP, what do you think would be a good match for the Sony's and the fiio amp? Would something like fiio's x5 or ibasso's dx-90 be a good choice? I've already tried sony's nwz-a17 with my triple-fi's, but I wasn't sold on the interface and the sound wasn't as spectacular as I was hoping for. Maybe I need to revisit it again to see what it sounds like with these Z5's.
So, to sum up. Bass unbelievable, soundstage incredible, fit actually better than the triple-fi's. Amped is the way to go from the start. Burning in should be interesting. Overall, very happy with the purchase.